Ocular melanoma is a common primary eye tumor of humans and causes both decreased visual acuity as well as death. Clinically, this tumor may follow an indolent, lengthy course over many years, or it may be progressive and lethal inspite of surgical removal. This unpredictable clinical behavior has generated controversy over the advisability of surgical removal since this may increase metastasis. Ocular melanoma has not been studied in vitro to any extent until recently because it had not been grown in culture as a continuous line. Now, however, we have developed a reproducible method for growing this tumor in vitro and have succeeded in establishing cultures which appear to grow indefinitely. The growth of ocular melanoma in vitro is not, surprisingly, like that of many other human tumors. Some clones derived from one tumor may grow for well over 100 in vitro population doublings without showing signs of stopping, while other clones from the same tumor may exhibit only a limited 40-50 population doublings. In other cases, all of the clones derived from a single tumor may exhibit similar growth, proliferating either continuously or for only a limited period of time. There is no evidence to indicate that the unpredictability of the clinical course of this tumor is in any way related to the variability of tumor cell growth in vitro. However, in this proposal, we outline experiments to determine if clones of ocular melanoma derived from the same and different tumors exhibit a different expression of tumor oncogenes as measured by transfection assays. By the use of DNA transfection in NIH-3T3 cells, and Southern blot hybridization methods, we intend to identify tumor oncogenes in ocular melanoma and determine if there is any correlation between oncogene activation and expression in different tumor clones and their in vitro growth as measured by population doublings. In addition, by the use of immunoprecipitation and electrophoresis, we will determine if the in vitro growth of ocular melanoma is related to quantitative or qualitative differences in the expression of the specific tumor gene product by examining clones with different in vitro growth potentials.